This invention relates to an apparatus for controlling operation of a clutch for a torque convertor in a transmission for a vehicle interconnecting an internal combustion engine and a driving wheel of the vehicle.
A torque convertor provided in a transmission for a vehicle as an automatic transmission or the like can have a clutch for mechanically transmitting torque from a pump side of the convertor to a turbine side thereof. It has been usual with this conventional apparatus that, in order to decrease slip loss at the torque convertor in the case of cruising of the vehicle at a high speed and thus improve fuel consumption, the clutch is arranged so that the engagement thereof is controlled in conjunction with a shift-up operation of the transmission to a higher speed stage. With this arrangement, during the driving at a high speed stage, the pump side and the turbine side are directly mechanically interconnected, so that there is no slip caused by fluid torque transmission. However, there has been a disadvantage that the torque amplification function which is the fundamental function of the torque convertor cannot be obtained. Consequently, acceleration and ascent ability of the vehicle at the high speed stage becomes poor.